The present invention relates to a home automatic baking apparatus comprising heaters for holding the temperature of bread dough at fixed level and baking bread efficiently.
Conventional automatic baking apparatuses of this type include an electric oven, a semi-automatic bakery oven shown in FIG. 1 (JP-A-60-36729) or an oven of hot-air circulation type shown in FIG. 2 (JP-A-61-1290). The baking apparatus shown in FIG. 1 is composed of a heating chamber 50 built in a body case, an upper heater 51 arranged at an upper part in the heating chamber 50, a main motor (not shown) arranged within a casing 56 in the vicinity of the bottom, a belt 55 and a pulley (large) 54 through which a removable blade 57 is rotatable at the top of a shaft 53 vertically arranged through the bottom, and a kneading case 56 with a lower heater 52 arranged around the outer bottom section thereof. After the processes of kneading, primary fermentation and degassing in the kneading case 56, the kneading case 56 and the dough are taken out, and the dough is divided, rounded and subjected to bench time process, after which the dough is formed and placed in a baking die. A baking pan is arranged in the heating chamber, and the baking die is placed on it for the secondary fermentation and baking. Also, as soon as the dough is baked up, the baking die, together with the baking pan, is taken out, followed by the bread, which is then placed on metal netting or the like for natual cooling to a level equal to about human body temperature before being served. In this type of apparatus, a thermostat or the like temperature sensor means mounted on the side wall of the heating chamber is used to turn on and off a heater to adjust the temperature in the heating chamber to the yeast fermentation temperature or baking temperature.
The semi-automatic baking apparatus of this type, therefore, is always accompanied by manual work for intermediate processes after the materials are set, so that the user is required to attend it through the approximately four hours of baking processes. Further, the operation of upper and lower heaters by a thermostat or the like arranged on the side wall of the heating chamber does not permit the internal temperature of the heating chamber to be regulated in detailed manner, but the fermentation and baking conditions require constant visual check. Furthermore, the use of upper and lower heaters of oven type for baking causes temperature variations between various parts of the kneading case or the heating chamber interior, thereby unavoidably leading to the bread head being baked in abnormally excessive brown as compared with the kneading case interior at the cost of taste. The baking apparatus shown in FIG. 2, on the other hand, is configured of a heating chamber 60 built in a body case, a fan motor 61 mounted on the outer wall of the heater chamber 60, fan casing 63 with a fan 62 driven by the fan motor 61, and a fan heater 64 around the fan 62 in the fan casing 63.
In both of these conventional apparatuses, the heating chambers 50, 60 have a large volume so that if a comparatively small object placed at the central part of the heating chamber is to be heated, a heater of comparatively large capacity (800 W to 1 KW) is often used with deteriorated thermal efficiency on the one hand, and the body case is too bulky to fit a kitchen position snugly on the other. Another disadvantage of these apparatuses is encountered when a comparatively large object is heated. In the former apparatus, the part of the object near to the upper heater 51 is baked to an excessively degree, while the central part thereof is hard to bake and the sufficient baking thereof takes a considerable length of time. In the latter apparatus, on the other hand, hot air is circulated along the directions of the shown arrows, and the resulting insufficient air distribution leads to a disadvantage similar to that of the former apparatus.
Further, the conventional semi-automatic baking apparatus of this type shown in FIG. 1 is not equipped with any room temperature sensor, but comprises a kneading case mounted removably in the heating chamber and a blade removably mounted on an upper shaft protruded through the bottom of the kneading case, wherein the heater energization is controlled by a thermostat or the like arranged on the side wall of the heating chamber thereby to control the temperature in the heating chamber. The dough temperature, therefore, could not measured directly. Also, in this semiautomatic apparatus, after the processes of kneading, fermentation and degassing all of which are conducted in the kneading case, the kneading case and the dough are taken out, and through the processes of dividing, rounding and bench time, the dough is formed and placed on a baking pan for the secondary fermentation and baking. Some of these processes always require manual work.
According to this configuration, the dough temperature which is easily affected by external temperature is controlled by upper and lower heaters to maintain the dough at the fermentation temperature, together with a timer to adjust the control and kneading time.
Since the temperature of the heating room is controlled by thermostat only, the dough temperature cannot be controlled precisely. Nor is it possible to meet fine fluctuations according four seasons and room conditioner in room temperature. When the room temperature changes from 10.degree. C. to 25.degree. C., for instance, the fixed manner of operation of the heater and motor does not allow for the temperature to be kept at about 30.degree. C. suitable for formentation, and the resulting overshoot of the heater raises the dough temperature to a level higher than 30.degree. C. The dough is thus over-fermented, making it impossible to produce tasty bread. Further, the semiautomatic construction is always accompanied by manual work for some processes, and the user is required to attend the apparatus through the whole period of baking. Another disadvantage is that the oven-type baking causes temperature variations in the apparatus with the frequent result that the bread head rather than the kneading case interior is baked up in excessive color.